Board Thread:General Discussion/@comment-26222858-20150917141812/@comment-25869229-20151003101415

I think the DT transformation is linked to the nerve system. If the nerve system picks up too much pain, it will send out a signal to the demon form. Like a back-up plan to keep Dante alive. If Dante were to not Devil Trigger, after a while of getting hit in the face with the devil bringer would probably cause some serious injuries. As you mentioned, Dante's skin becomes much more solid and harder to break when in Devil Trigger form, like if it was made of stone. I think the nerve system was interrupted by the Devil Bringer, which prevented Dante from fully using the DT. TL;DR Nero's beating stopped Dante's nerves from activating the Devil Trigger.